package top.appx.util;

import java.util.Random;

/**
 * Created by zwyhome on 2015/5/28.
 */
public class StringUtil {
    public static boolean isEmptyOrNull(String str){
        return str==null||str.length()==0;
    }

    public static String randomCheckcode(){
        int r =(int) (Math.random()*9000+1000);
        return r+"";
    }
}
